Many conventional motor vehicles, such as the modern day pickup truck, are equipped with a pivotable end gate that closes off the end of a rear storage area. The traditional end gate (more commonly known as a “tailgate”) is a door assembly extending transversely across the width of a rear portion of the vehicle. The end gate is normally hinged to the vehicle body at opposing side edges, near the bottom of the door assembly. The end gate is often mounted to two rear pillars between body side-panels that cooperatively form a vehicle storage area, such as the bed or box of a pickup truck or the rear cargo compartment of a sport utility vehicle (SUV). The end gate is operable to be unlatched, and swung from a vertical, closed position to a horizontal, open position that is approximately coplanar with an interior floor surface of the vehicle storage area.
Some end gate assemblies include a counterbalancing hinge assembly for assisting movement of the tailgate during opening and closing thereof. Different hinges can be used to produce various desired hinging characteristics. Torque (or torsion) rods have been used within prior art hinge devices to aid in hinging the end gate to the vehicle body. Deflection of the torque rod is used to counterbalance the weight of the end gate to aid in the opening and closing thereof. Specifically, the torque rod reduces the effort required to raise and lower the tailgate by storing energy in the twisting of the torque rod during opening/lowering from the residual kinetic energy generated by the tailgate.
Added mass from an end gate storage module and mass from stowed objects adversely effects the counterbalance by increasing initial and peak closing efforts and damped opening performance. Thus, there is a desire to have a counterbalance mechanism to compensate for additional mass storage in the end gate storage module.